1. Technical Field of the Invention
The present invention relates to a method and apparatus for surface polishing which includes surface washing of various kinds of containers and vessels such as tableware, utensils and parts, and various surface finish treatments such as mirror finish treatment, plating treatment, and pretreatment for plating process.
2. Description of Related Art
In a conventional tableware washing machine, a method of injecting liquid detergent toward tableware supported by a rack or basket is generally being adopted. However, there is a problem that a stain firmly stuck to tableware can not be removed completely.
In Japanese published unexamined patent application No. 3-202037, there is disclosed a tableware washing machine which is provided with a liquid detergent agitator, a vibrator for vibrating liquid detergent, a grasping device for grasping particles at a predetermined position and a liquid detergent heating apparatus wherein a rack for supporting tableware is provided in a case which accommodates a liquid detergent into which particles of different masses are mixed. In the tableware washing machine, a liquid detergent is flowed by stirring the liquid detergent with the agitator, and with the flow of the liquid detergent, the liquid detergent and the particles of different masses are brought in contact with the tableware whereby stains stuck to the tableware are removed. By vibrating both the liquid detergent and particles, even a small spot stuck to the tableware is removed. Furthermore, by seizing the particles when the liquid detergent is discharged, stains and particles are separated.
However, there are problems even in the tableware washing machine described above. First, washing effect is not sufficient even particles are brought in contact with the tableware accompanied with a flow of the liquid detergent since the velocity of the liquid detergent generated by the stirring is small compared with a case of an injection method, and the amount of particles which can be filled in is limited. Secondly, it may be considered that a washing effect might be improved by vibrating the liquid detergent with the vibrator, however, if a particle made of soft resin or elastic resin is used in order to protect tableware from being scratched, the vibration of the liquid detergent is absorbed and washing effect can not be sufficiently effected. Thirdly, even if a mixing ratio of particle is increased to raise the probability of contact with tableware by stirring up the liquid detergent, it causes a difficulty in stirring up the liquid detergent, and it can not contribute to improve washing effect. Moreover, stains of tableware can not be effectively removed since vibration of the liquid detergent by the vibrator is absorbed by the particles.
In Japanese published examined patent application No. 61-42575, there is disclosed a method of washing tableware thrown into a washing tank wherein beads and a liquid detergent in less amount than to fully fill up gaps between the beads are accommodated, and by vibrating the washing tank, the beads are moved in circulation along an inclined plane. However, even in such a tableware washing method, unless the liquid detergent is small in amount, washing can not be sufficiently performed by moving the beads in circulation. On the contrary, if the amount of the liquid detergent is too small, washing effect is remarkably dropped thereby inviting a problem to cause a difficulty in controlling the amount of liquid detergent for a stabilized washing effect. Furthermore, a washing process can not be sufficiently effected since the liquid detergent is small in absolute quantity. Since the washing tank has to be largely vibrated, it is required to provide countermeasures for noise and vibration.
In a mirror finish treatment, a barrel finishing method is adopted wherein metal balls and an object to be treated are accommodated in a rotary barrel when an object to be treated is small in size, and the barrel is rotated for a finishing process. However, there is a problem that washing can not be effected satisfactorily and accurately. For a comparatively larger object, there is left only a manual buff finishing method, however, washing effect is extremely lowered. In other conventional methods such as chemical polishing, barrel plating, pretreatment for the barrel plating and barrel electrolytic polishing, high-grade treatment can not be effected, and moreover, structure of an apparatus becomes complicated.